When the global search engine Yahoo! says it collects ten terabytes (a staggering ten trillion bytes) of consumer data every day, it is no surprise that advertisers are spending big money on steering internet searches in its direction.
Yet figures from the Internet Advertising Bureau and PricewaterhouseCoopers still manage to astonish: UK spend on paid-for search shot up by 52 per cent in 2006. That's £1.2 billion spent by advertisers to secure the sponsored links that appear at the top of search results pages - and 57.8 per cent of the entire ad budget spent online during the year.
Despite the enduring "Wild West" nature of the search market, where deals are fast-paced and much territory is still largely uncharted, marketers are happy to hitch their wagons to search engines.
One compelling reason for advertisers to spend so much money on search is that it appears to work. It is direct marketing in its simplest form: a consumer is searching for a product, and if they can find your business, you've got a good chance of making a sale.
Evidence shows that offline advertising boosts search activity online. Recent research, published jointly by Yahoo!, Hitwise - which measures search and web traffic - and the digital media agency i-level, analysed data from brands including the AA and Sky over a six-month period.
It showed that when TV spend doubled for the AA, for example, there was a 70 per cent increase in the number of internet searches that included the terms "the AA" and "car insurance".
"Search grew up on pay-per-click and direct response, so it's no surprise that categories such as finance and travel spend so much on it," Guy Phillipson, the chief executive of the IAB, says. "Increasingly, advertisers are understanding that their offline ads encourage search.
"When it comes to search, if you're not there, one of your competitors will be. It's not surprising that eBay and Amazon pick up business from offline competitors that haven't optimised their search."
Even FMCG brand owners, many of whom are convinced that consumers don't search for them online, may have more reason to invest in search than they might realise. While few people might go on to the web to hunt down, say, Colgate or Flora, they are definitely searching for "teeth whitening" and "healthy diet". As Phillipson says: "Brands have to understand how to own their brand territory online."
It is the same drum, inevitably, that is being beaten by Google, which handles nearly half of the web's global search queries. The search engine has deliberately plundered traditional media and ad agencies to build a team, under the UK sales director Mark Howe, which is going out to digital and full-service agencies evangelising about the power of search.
Howe believes Google can show advertisers how incorporating search at the beginning of campaign planning can stimulate more consumers to search for their brands online. So, bidding on an ad campaign's tagline (such as Norwich Union's "Quote me happy") can guide potential customers more directly to the advertiser's site. The argument finds tangible form in developments such as the acquisition by the Engine Group of the search agency Eyefall, to sit alongside disciplines such as advertising, in WCRS, and digital at Meme.
However, other commentators believe the dream of search experts sitting side by side with the creative team at brand strategy meetings is more the preserve of a few, more forward-thinking brands, rather than the norm - at least for now.
And some, such as Andy Bush, the publishing director for Europe, the Middle East and Africa at The Fortune Group, which includes the website CNNMoney.com, views the drive to "keyword" ad slogans largely as a revenue-boosting ploy by search engines. Surely consumers are most likely to search by brand name, or, failing that, by product sector, he argues.
"It has to be about what consumers want, rather than advertisers making that call for them," he says. "That's the danger."
So, what trends are underpinning the exponential growth in search?
Jim Brigden, whose agency The Search Works handled around £50 million in search billings last year, notes that clients are taking a far more strategic, long-term approach.
Another noticeable trend is the "uncapping" of budgets as marketers realise the efficacy of search advertising. Paid-for search works by advertisers bidding for keywords and phrases that they think will drive relevant customers to their websites. The search engines receive a payment every time a customer clicks through on one of the sponsored links.
In the past, there had been fears that advertisers that had bid on expensive keywords - a term such as "car insurance" can cost as much as £15 per click, for example - could end up paying high amounts without necessarily converting the clicks to sales.
But Brigden says: "Advertisers are saying that if (search experts) can deliver a positive ROI, then marketing budget is uncapped."
He predicts search will eventually move to a cost-of-goods-sold model, alongside other fixed necessities such as the electricity bill or staffing costs. "You don't close your shop at 6pm if you have got a hundred shoppers inside," says Brigden. In just the same way, marketing directors will not cease their search marketing programmes if they still deliver customers.
One of the ways in which experts are improving their understanding of how consumers search - and, therefore, finding the most effective keywords on which to bid - is by following their "click journeys".
New Artemis software from Media Contacts, the digital arm of the media agency Media Planning Group, is claimed to track the entire route a customer takes from the beginning of an online search to making a purchase.
Someone might be searching for a holiday, and then narrow that search into holidays in Spain, and then holidays in Spain with a particular company - a process that can sometimes take three months and up to 15 clicks. Previously, the advertiser may only have known the final search term on which the customer clicked before making the purchase. Artemis makes the whole journey visible.
"Instead of attributing all the return on investment to the final keyword, we can see what a user types in. You really need generic terms to trigger a journey," Grant MacFarlane, Media Contacts' head of search, says.
One of the most significant developments will be the long-awaited launch in the UK of Yahoo!'s Panama, which is a new system where search rankings will be based on a combination of the amount paid and a "quality" score. The aim is to improve advertisers' keyword bidding, and make search results more relevant for consumers. The quality score is derived from a combination of elements, including the number of click-throughs that a search result achieves. Previously, ad rankings were determined solely by price.
Panama is the result of two years of conversations with advertisers and the input of 400 engineers, according to Richard Firminger, the regional sales director at Yahoo! Search Marketing. "Before Panama, lazy advertisers could become the top search just by paying for it, but the new system won't let an advertiser hog a position solely on price," he says.
"What will rise to the top are good-quality ads based on how consumers rate their relevance."
Yahoo! is banking on the system to help it fight back against Google (which already ranks search in a similar way) and reassure shareholders. "It's built to be scaleable," Firminger says. "It doesn't matter if mobile search is the next big thing or something completely different we don't even know about yet. Everything can be sold through this one platform."
There are also somewhat less concrete developments on the horizon. Alain Portmann, the global media director of the full-service digital agency Web Liquid, is anticipating the growth of "social search".
"As people become more adept and experienced with the internet, they realise that their requirements from search engines are evolving," Portmann explains.
And, as more and more people spend increasing amounts of time on search engines, brands will need to find ways of harnessing their changing behaviour - behaviour such as "Wilfing", or "What Was I Looking For?" (see box, left).
As MediaCom has identified, the advertising fraternity has had to move from an era of "interruption" of consumer activity to one of "engagement", and is now moving to a further period of "dialogue".
Finding the right tone of voice with which to "dialogue" with consumers is crucial. Some advertisers are getting it right. Others, less so. But for all, the search must continue.
WHEN SEARCH GOES WRONG
When Pontiac challenged TV viewers in a US ad campaign to "Google" its brand, a Mazda executive did just that, and realised that Pontiac hadn't bought the sponsored search links. He snapped them up for Mazda.
Although there haven't been such high-profile incidents in the UK, a quick survey of an ad break on ITV1 during The Bill reveals that advertisers aren't always making the most of potential search spikes that their ads may generate.
For example, the yoghurt brand Muller's latest campaign asks viewers "do you lick the lid?". But typing those words in to Google links to a story about the campaign, but not to any Muller site.
Type in the strapline,"Lick the lid of life", and Muller's microsite is the fifth and sixth link to appear in the natural search. But the links don't work - at least they didn't on 3 May.
Howard Brown has returned to TV screens in an ad for Halifax's tax-free savings. Typing "Halifax ISA" in to Google shows that the brand has the number one paid-for search result and the top natural result; but a search for "Halifax tax free" reveals that the number one paid-for spot has been bought by you, the taxpayer, to promote the Government's website direct.gov.uk.
Affiliates - Websites that derive income from sending traffic or customers, or delivering sales, to other websites.
Brand-term leakage - The percentage of searchers who use your brand-term, but do not immediately arrive on your site, going instead to a competitor or affiliate site.
Click fraud - The phenomenon of affiliates generating revenue by having people or automated systems repeatedly click on links to artificially drive traffic to a site.
CPA - Cost per acquisition, or the amount of money paid for each customer acquired.
CPC - Cost per click, or the amount of money paid every time someone clicks through on a sponsored link. Also known as PPC (pay per click).
CPM - Cost per thousand, or the amount of money paid every thousand times your ad is served.
Natural search - Results generated by a search engine's algorithm, rather than those that are paid for.
Paid-for search - Results that are usually featured at the top of a search page under sponsored links, and are generated for whoever has bid highest on the search term or keywords entered by the webuser.
Search optimisation - The practice of developing a website to ensure it's listed as high as possible in natural search rankings.
Trademarking - Making sure search engines recognise brand names and trademarks so that other brands cannot bid on them for sponsored search.
TEN MINUTES 'WILFING' WITH ...
"Wilfing" ("What was I Looking For?"): A term coined by moneysupermarket.com to describe the habit of being distracted from the website you were first searching for. "I don't particularly want to write this as I'm amusing myself reading an article about internet boot camps in China.
"Apparently, addiction to the net in China is so rife that it has been given equal status to alcoholism and gambling. Now, I'm no ice-hearted nasty, but I can't imagine finding the sympathy to sponsor a colleague to cycle backwards across the Andes to raise money for all the poor ickle web junkies in Hackney. It's the internet, for God's sake. Turn it off.
"Why am I reading this anyway? Hit the back button to return to what I started searching for - wilfing, the art of surfing the web without any real purpose. Find myself looking at an article I read earlier about an engineer from Wisconsin who has invented a 70mph Portaloo. Spot link to Chinese internet boot camps article. Hit back button again.
"Different site now. This time it's about the Scumball 500, the alternative Gumball rally for the financially challenged. Make mental note to ask for a pay rise. Spot link at bottom of article: Modern fangled water closetry. Hit the back button again.
"Here we go. Wilf.com. With lots of pictures of pretty thirtysomethings. In lingerie. Looking compromised. Quickly check address bar: Milf.com. Hit back button, frantically ..."